LAUREL, MD, NOVEMBER 1, 2016 -- Hindsight is 20/20, especially when it comes to infrastructure investment. Water mains, roads, bridges -- many need replacing. While the investment can’t be made overnight, Washington Suburban Sanitary Commision (WSSC) is making an innovative change to water main replacement, greatly benefitting generations to come.
Zinc-coated ductile iron pipe and V-Bio® Enhanced Polyethylene Encasement are now standard materials. Traditional ductile iron pipe lasts about 50-75 years. When it breaks or wears out, municipalities will dig up roads to replace a section -- sometimes even a mile or two -- of old water main. That costs money and it’s an inconvenience. By switching to zinc-coated, V-Bio® encased ductile iron pipe, WSSC expects to put that pipe in the ground and not come back to replace it for 100 years or more.
The protective zinc coating on the ductile iron pipe provides active corrosion control. The V-Bio® encasement is an additional level of active protection that works in concert with the zinc coating. It targets anaerobic bacteria activity and inhibits the formation of corrosion cells under the wrap.
"Our engineers are always researching, studying and collaborating to come up with sustainable, smart and financially responsible solutions for our customers," said Carla A. Reid, WSSC General Manager/CEO. "The switch to zinc-coated ductile iron pipe means the replacement cost for future generations will be greatly reduced."
"Zinc-coatings have been successfully used in Europe for decades and now WSSC is the first water utility in the country to make zinc-coated pipe with V-Bio® film standard materials," said Allen H. Cox, P.E. Ductile Iron Pipe Research Association Regional Director. "This combination highlights the Commission’s commitment to employing innovative solutions to benefit its customers."
KC Water in Kansas City, Missouri is believed to be the first water utility in the United States to use zinc-coated ductile iron as a standard material for water main replacement. WSSC is believed to be the first to use the combination of zinc-coated ductile iron pipe and V-Bio® Enhanced Polyethylene Encasement.
WSSC’s Infrastructure Snapshot
Total Miles of Water Mains: 5,794 miles of water mains
Distribution System - 4,947 miles (less than 16-inch diameter pipe)
Transmission System – 847 miles (16-inch and greater diameter pipe)
Water Main Replacement
55 miles per year (under 16 inches)
6 miles per year (16 inches and greater)
Age of Water Mains (in years)
Over 50: 2,229 miles (38 percent)
25 – 50: 2,153 miles (37 percent)
10 – 25: 941 miles (16 percent)
Under 10: 462 miles (8 percent)
Unknown: 9 miles
Water Main Replacement Cost: $1.6 million/mile (small diameter – under 16 inches)